Telephone system



MarCh 24, 1931. w Q, PAssMORE 1,797,788

' TELEPHONE SYSTEM Filed Oct. 1, '1928 s Sheets-Sheet 1 Inuenlur' Millz'am 512 123 Passmnrs March 24, 1931. w. o. PASSMORE TELEPHONE SYSTEM Filed Oct. 1, 1928 5 Sheets-Sheet 2 I'FLUETL DP InIiHiam [191253 11 Fassmnre March 24, 1931. w PASSMQRE 1,797,788

TELEPHONE SYSTEM Filed 001;. l, 1928 3 Sheets-Sheet 3 Fig.3.

'enTE WILLIAM ocrnnsnv rnssnonni cr}, IvE:BPooL, ENGLAND, nsszenonfiro hssociemnn TELEPHONE AND TELEGRAPH COMPANY, ornnnsns o r MISSOURI, CQBIE'ORA TION OEIDIELAWABE i j temomssswm Application filed October 1e28, s nsin soasesiana in Great Britain November is, 1937.

, The present inventionrelatesto telephone systems in general but is in'ore particularly concerned withl small automatic exchanges such as will often form private-installations. The main object of theinvention is toprovide a system of this type'whi'ch will require the minimum amount of apparatus for discharging all the necessary functions and which shall also be very reliable so that little orno attention is needed to maintain it insatisfae tory order. 9 1 1 f According to one feature ofthe invention a reduction in the amount of apparatus required is effected in that connection is adapted to be made with both calling and called parties overthewipersof the same switch, all of said wipers beingfrigidly connected toth v. i v v1; According to another, feature of'the invention, a two-directional switch is employed having a capacity equal tothesqua're of the total number of lines in the system; connec tion being effected with the calling line on the first motion and with the called line on the second motion of the switch. I

Another feature of the invention is the'use of a two-directional automatic switch of the vertical and rotary'type having its ba'nkcon tacts arrangedin levels and having two sets of ;wipers; the contacts eng age'd'by, one set being multipled vertically 'throughout the bank, while those engaged by-the other set are multipled horizontally throughout 1 the bank. Still another feature ofth invention is the provision of an automatic switchf adapted to move its wipers to perform a hunting oper ation to connect with 21 calling-line and subsequently to again move said wipers in response to impulses transmittedfrom said line.

These features will be better appreciated from the following detailed description of, 7

make a call, the'start relayS of'which only 7 one method of carrying the invention into efiect which should be taken in conjunction with the accompanyingdrawings: 'It will'be understood however that the arrangement described is given by way ofexample only and that Various modificationsto the circuit de tails could be made by those skilled in the art without exceeding the scope of the-invention.

Tlie'system "considered is assumed to'com priselolines only, and it is assumed further that'for such a systemtwoconnecting circuits tionalcircuits can be addedat any time with V out difiiculty. A connectingcircuit comprises a two-directional switch of the well-known vertical and rotary type having sixwipers each with a 1'00-pointba'nk and also a vertical wiper for controlling the hunting operation of the switch; The'sequence of operations is that when'a subscriber removeshis receiver to make acall, the next available switch operates vertically to find his line with which connection is made over one set of three wipers and the switch 'isjthen' rotated by dialled impulsesto connect with the wanted partys line overthe remaining three wipers; Owing to the specialarrangement of bank mu'ltipling which will be. [de scribed fully subsequently, when connection has once beenmade' with a callingline it is maintainedwith this line over the finding wipers throughout the Totary motion.

' Referring now to the'drawings comprising the banks engagedby the wipers for'connectingwith the called party, while Fig. 5 shows the commoning of the banks in which calling lines terminateQ The drawings should" be placed so that Fig. 2 isto the right of Fig. 1 andFig. 3 is'below Fig. 2,'with the corresponding lines in" alignment.

VV'hen the subscriber A lift-s his receiver to one is provided, is operated from earth on resting armature 13,"swit ch-hook springs 12,

impulse springs 10, transmitter TR, receiver RE,frest1ng-armature 15, resistance 11, con

ductor 20, winding of the start relay S to battery. fThis earth is also extended over restinglarmature 14 to the contact associated with the line of subscriber A in the vertical vertical magnet VM over armatures 3i, L6

v and 2a, relay E also operating in shiintwith the magnet to disconnect the busy tone cir magnet circuit at armature 53. magnet energizes and raises the wipers lo'i8, 2i and -62 one step thereupon bringing the test wiper 21 into contact with the lirst contact of the Vertical -test .bank. l he opening of thevertical magnet springs releases relay D and therestoratioii ofireiayi) opens the circuit of the verticalma'g: net winch releases closing its-springs '2'2and again comp eting the circuit of relay 'l'his interrupter action ,between relay D (which is slightlyslow releasing as its upper winding is short-circuited by armature, 38 of relay PA) and the vertical magnet is continued till the test Wiper 21 encounters the contact in the vertical bank which has been earthed over the calling subscribers vloojp. When this occursrelay F'or will operate from this earth over the resting armature'28 of relay BA. The circuit forthevertical magnet is now opened at, armature 46 and a circuit is completed insteadfor rotary magnet RM. The rotary magnet operates and steps the wipers 167 -18 and '6062 on to the first set of contacts, at tlie'sanie time movingwiper 21-away' from its bank so thatrelay FG de-' energizes. Earth from wiper 17 now operates the cut-oil relay CO andalso serves to guard the calling subscriber in the called banks of the connectors. The operation of cut-oil" relayCO opens the circuit-0t the start relayfS which restores thereupon opening the circuit of relay D, and also removes earth from the vertical test bank contacts. .As the Wipers are now engagingthe first set' of contacts, the circuit of impulse relay'A is coin pleted and relay A operates over the calling loop, thereby operating relay BA at. armature 2'3 and this in turn operatesrelay ,B at armature 30'. The operation of relay BA prepares a new circuit for relay EG'at armature 28, at armature 29 prepa1'es tlie,holding circuit for the ringing trip and switching relays,

L andatarmature 31 prepares the impulsing circuit to the rotary magnet. Relay B upon operating, at armature 24: V disconnects the vertical magnet,at armature .25 opensthe rte lease magnet circuit .;'at armature-26 earths conductor 78 to start the busy tone, ringing and interrupter relays, and at ar1-nature 27 switches the start lead to lead 7 7 extending to the second connectorgroup so tliatanother caller, may take-this second circuit. It will-be convenientito consider indetail the operation of the tone and ringing relays at a later stage, and it will suflice for the moment to say that an intermittent howler or similar tone is available on conductor 7i for calling an intermittent tone on conductor 7 6 for busy signal and a similar but continuous tone on conductor as a dialling signal. The subscriber now hears a continuous tone connected up from conductor 75 over I I w i n v 7 condenser48 and resting armature 33 to his cuit at armature a9 and to open the -release: The vertical j device. "It will be noted that the switch has made an initial rotary step in itsfinding operation and under these circumstances it is necessary to absorb the first dialled impulse in order toretain the full availability of the banks. The first impulse therefore operates the two-step relay PA, and the remaining impulses are then transmitted to the rotary magnet, Impulse relay A responds to the impnlsesfrom'the calling device, and onitsfirst restoration extends earthfrom restingarmature 23- over armatures 25, 47,, 58 and 36, lower winding of two-step relay PAto battery. Relay PA closes its light tensioned armature 35, therebyshort-circuiting its upper winding to earth on ofi-normals rings 41 until relay ,A rte-energizes. Relay ISA then operates all its armatures, and at'armature 33 (llSCOIlnects dialling tone from the subscribers line, at armature 37 completes the circuit for the remaining impulses to be routed to the rotary magnet and at armature 38 removes the short-circuit from the upper winding of relay The rotary magnet responds to the remainder of the impulses over a circuit which may be traced from earth,

armatur'es 23, 25, a7, 58, 31, 37 to the rotary magnet tobattery and steps the wipers round. in known manner to the desired .line, relay E energizing in parallel with the magnetand providing an alternative circuit for the rotary magnet at armature 52 in case relay FG should operate asthe test wiper 60 called subscriber is-already engaged either as calling, or called party, wiper 60 will encounter earth which is extended overarmature 32, armature 50 before'shunt relay E releases,armature 28', winding of relay FG to battery. Relay ,FG operates thereupon at armature 45 preparing alocking circuit for itselfwhich will become efi'ective when shunt relay E releases, at armature47 opening the rotary magnet circuit toprevent any further impulses affecting therotary magnet, andat armature-44 completinga tone circuit from intermittent tone conductor 76, condenser 54, armatures 49 and 44, to the calling subscribers line. The calling subscriber hearing the intermittent tone accepts this as an indication that the wanted subscriber is-busy and.

replaces his receiver, allowing the switch to return to normal as described later. i 7

If the wanted subscriberisfree, no earth is encountered by test .wiper 60and as soon as shunt-relay E releases, a circuitlis comjpleted for switching relay H from earth, armatures 29, 34,45, lower low resistance winding of switching relay H, armatures 50 and 32, test wiper to battery through the called subscribers cut-off relay such as CO. The cut-ofi' relayoperates to: clear the called subscribers line of its normal earth and battery connections, and switching relay H, closes its light tensioned armature: 57 thus completing the circuit of its second and locking Winding which serves to operate all its armatures. Switching relay H-opens the rotary magnet circuit at armature 58. to prevent the rotary magnet being operated-by any further impulses, at armature 56rextends full'earth to the test wiper 60 for guardingpurposes, and at armatures 55 and 59 extends the ringing or howler circuit to the called lines. An intermittent loud tone is now'connectedvfrom conductor 74, upper; coil of ringing trip relay F, armatures 41 and 55, wiper 61, called subscribers line and instrument, wiper-5 62,

armatures 59 and 43 to earth,relay F not-being operated with this. current. The loud tone actuates the receiver atthe' wanted station calling the attention ofthe subscriber.

It will be appreciated that ringing current to actuate a bell at the desired instrument could be. connected in a precisely similar manner. but the arrangement of the kind'described would probably be entirely satisfactory in a system of the kind considered-with a saving in the cost of the subscribers bells.

n indication to the calling subscriber that the wanted party" is being called isaflorded bythe leak condenser 51 connected between the calling s'ubscribers talking condenser and the outgoing ringing or ihowler circuit.

When the'called subscriber lifts his receiver to reply to the call, a direct current bridge is completed across his lineand this causes relay F to operate'its light tensioned armature 81 and complete a circuit for-its second and locking winding. -Relay F now operates all its armatures, thereupon at; armatures 41 vand 43' extending the circuitof the calling subscriber to that of the called subscriber by way of the speech condensers,

and 82. Battery feed for the called subscribers instrument is supplied by relay D,

which is connected across the called sub-- the calling subscriber replaces his receiver. The circuit of impulse relay A is thus broken and in turn relay BA'releases and opens the circuit of relay B. The circuitaof the'release magnet Z is then completed from; earth, ar-

matures 23, 25 and 53,0fi-normal springs 42, winding of release magnet Z to battery. The 'operation'of the release magnet Z restores the shaft and wipers to normal position where theoff-normal springsare opened and therelease magnet circuit broken. Relays F and H restore as their holding earth is removed by the release of relay BA and re- IlayPA'restoreswhen the shaft is normal and hasopened the oif-normaljsprings 41.

The production-of the various tone signals may nowbe considered in'more detail. As mentioned above, the tonesthemselves are generated x and the necessary interruption provided by means of relays. When the connector switches through on finding the calling subscribers'line, earth'is connected to the tone and interruption circuits over conductor 78. Considering'firstthe busy tone circuit, relay BR, Fig. 3, is operated by this earth and at armature 63 breaks its own circuit thereby setting up a rapid self-interrupting operation. 'A conductor connected to the centre point to the two windings of relay ER is taken over armature 73 of relayI of the interrupter equipmentto conductor 76, this arrangement providing an intermittent tone on the conductor 76', the design and adjustment of relay BR giving tone of the desired frequency. The action of the howler'tone relays R and V issomewhat similar and will 7 T when itoperates- The-arrangement is such a that an intermittent tone of suitable strength and frequencyqfor calling the wanted subscriber is suppliedto conductor 74, and also a similar but continuous tone is supplied to conductor 7 5Iand this when passed through the 'low capacity condenser 48 is suitable as a dialling indication. 1 Q

. The interrupter group of relays consists of threeslow acting and releasing relaysl I and I soarranged that they operate each other in turn, thelast one to operate releasing the first'which then releases the second and in turnthe third. This sequence ofoperations continues indefinitely and at a constant rate, the circuits requiring to be incircuit and armature 78 on relay I interrupts the busy signal circuit. V t 7 hat claim as' new and liettersPatentisz- 3 V =1. In; an automatic switch, (two sets of wipers for connecting res ectively with call ing and-called lines, an "means including both sets of 'wip'er's for extendinga connecdesire to secure tion 'froma calling lineto a'called line;

In an automatic switch having a plu rality'oi wiper's'controlledby the sa'me'stepping magnets, for automatically operating the stepping magnets to extend a connection to a callingf-line via certain of said- Wipers, means thereafter eflective for directively operatingone'stepping magnet to extend a connection to a' called line via other of said wipers while maintainingsai d first connection intact- V I 3. In an automatic switchhaving'two' sets of'wipers mounted-onthe same shaft, means for moving the shaft to causeone set of wipers to connect with a calling lin'e,'and means for again moving the shaft' to. cause the-other set of wipers to connect with a called linewhile maintaining the connection with the calling line intact. V

4. In an automatic switch havingtwo-sets of wipers mounted" on the same moving element, means for operating *said element to connect with a calling-line via oneset of wipers,-and means f orreoperating said element'to connect with a called linefvi a the other setofwipers while maintaining said first connection intact. Y 1 5. inatelephone system, ali-ne, an automatic switch having access to said line in a plurality of different positions,"an'd' means for operating said switch tofconnect with said line in a particular position determined by whether the line is calling or being called.

65 Inatelephone system,fa line, an automatic-switch having access "tosaid 'line in two difi'e'rent positions, and means ior operating said switch to connect with-said linein one or" the other oif'said positions depending on whether'thelineis calling or being? called;

7. In a two-directional switch for connect-V- ing with calling and, called lines, means for selecting a 'fcall-ing line responsive to the first motion of the-switch, and means for connecting'with a called line-responsive to the secondmotio'n'of the switch; I

,, 8. In a' tclephone system, a two-directional awe-vac switch having a capacity'equal' to'the square of the number of lines in the system, means for selecting a calling l ine responsive to the first motionof the-switch, and means for connectingjwith a called line responsive to the second motion ot the switch.

banks, and multiple connections between adjacentcontacts in each row in the other of said'b'anks." L

10. In a telephone system, an automatic switch ha'ving'wipers, meansfor moving said wipers to establish a connection with a calling line, and means for-subsequently moving said wipers responsive to directive impulses transmitted over the/calling linewhile main taining said first connection intact.

.11. In a telephone. system, an automatic switch-having two-sets of wipers, means for establishing a connection with a calling line via one set of Wipers, and meansefiective responsive to such connection for establish-- ing a connection with a called line via the other set of wipers; I

12. Ina telephone system, an automatic switch having two sets of wipers, means for establishing a connection with a calling line via one set ofwipers, means efi'ective responsiveto such connection for establishing a connection with a called line via the other setof Wipers, and means for connecting a signalling current to the called line.

- 13. In a telephone system, a linecomprising twoconductors terminating in a set of contacts accessible to an automatic switch, a test'contact for said line, and means responsive to a call on saidline for connecting-a characteristic potential to. said contact via the calling'line 100p; 1

141 In a telephone system, a line comprising two normally disconnected conductors, a-potential connected to oneof said conductors, a test contact connected to the other of said conductorsyand means for connecting said conductors responsive to a call on said 15. In a telephone system, a line comprising two talking conductors extending from a subscriberls station and terminating in a set oi contacts accessible to an automatic switch, a test contact for said line connected to one of said conductors, a source of direct current connected to'the other of said conductors, and means responsive to a call from the station for connecting a direct curren bridge across said conductors.

' 16. In 'a telephone system, a line comprisingtwo conductors terminating'i'n a set of contacts accessible to automatic switches, a

, stepping magnet operated only automatically test contact individual to said line, a common start relay for said switches connected in multiple with said test contact, and means responsive to a call on said line for connectmg a characteristic potential to sald contact 7 .to calling lines by way of wipers, means for and said relay via the calling line loop.

17. In a telephone system, a plurality of subscribers lines each comprising two talking conductors terminating in line contacts accessible to automatic switches, a test contact for each line connected to one of the talking conductors, a starting conductor for the automatic switch common to all lines, and multiple connections including a resistance individual to each line from said starting conductor to the said talking conductor of each line.

18. In a switching mechanism having an automatic primary hunting movement and a directively controlled secondary movement for extending connections between calling and called lines, a primary stepping magnet, and a relay for initially controlling the operation of said magnet and for subsequently feeding talking current to the called line.

19. In a vertical and rotary switch having access to calling and called lines by way of wipers, means for initially automatically moving the wipers into engagement with a calling line, said initial movement comprising one or more vertical stepsand one rotary step of the wipers, and means for directively moving the'wipers into engagement with a called line responsive to impulses transmitted over the calling line, said directive movement comprising one step less than the number of directive impulses transmitted.

20. In a vertical and rotary switch having access to calling and called lines by way of wipers, means for automatically imparting one or more vertical steps and one rotary step to the wipers to effect engagement with a callingline, means for receiving a series of directive impulses from the calling line,

. means for cancelling the first impulse of the series, and means responsive to the subsequent impulses of the series for imparting a corresponding number of rotary steps to the wipers to eflect engagement with a called line.

21. In a two-directional switch having'vertical and rotary stepping magnets, means effective for operating the vertical magnet only to perform an automatic hunting operation, and'means elfective for directively operating the rotary magnet to complete a connection.

22. In a two-directional switch, a vertical for controlling the primary motion of the switch, and a rotary stepping magnet automatically operated in its first step and di rectively operated in its subsequent steps for controlling the secondary movement of the switch.

23. In an automatic swit h having m0ve- V means for subsequently moving said wipers whilemaintaining said connection intact.

24. In an automatic swltch havlng access stepping the wipers into engagement with a calling line, and means for further stepping the wipers while maintaining the connection with the calling line.

25. In a switch for establishing connections with calling lines by means of wipers, automatic means for stepping the wipers into connection with a calling line, and directively controlled means for further stepping the wipers while maintaining the connection established with the calling line.

26. In a telephone system, a line terminating in a set of contacts, a switch, means for automatically operating said switch to connect withthe line via said contact set, means directively controlled over the line for further operating said switch, and other contact sets multiply connected with said first 

